From Longman Dictionary of Contemporary Englishnecklineneck‧line /ˈnek-laɪn/ noun [countable usually singular] DCthe shape made by the upper edge of a piece of woman’s clothing around or below the neck a square necklinelow/plunging neckline (=leaving part of the chest uncovered) Her evening gown had a plunging neckline.
Examples from the Corpus
neckline• Top A neat fitting top with a flattering neckline and self-covered buttons down the front. 100% cotton jersey, machine washable.• a black dress with a low neckline• Above the scoop neckline of her peacock blue dress, an ill-defined rash of mottled pink broke out, then faded.• It has a low, scooped neckline front and back and high-cut sides to flatter your legs.• Team eye-catching checks and a fitted blouse with a sweetheart neckline, for the ultimate in 50s glamour.• The neck was low and a narrow double ruffle decorated the neckline.• I then cut out the neckline and sew in the usual way.• To decrease the depth of a V neckline, deduct 1 from this figure for each 0.5 centimetre required. 